rigid lock

Module: solid

Category: nlconstraint

Type string: "rigid lock"

Parameters

Name	Description	Default	Units
body_a	body_a	-842150451	[]
body_b	body_b	-842150451	[]
laugon	Enforcement method	1	[]
tolerance	tolerance	0	[]
gaptol	gaptol	0	[]
angtol	angtol	0	[]
force_penalty	force_penalty	1	[]
moment_penalty	moment_penalty	1	[]
joint_origin	joint_origin	{0,0,0}	[]
first_axis	first_axis	{0,0,0}	[]
second_axis	second_axis	{0,0,0}	[]
minaug	minaug	0	[]
maxaug	maxaug	10	[]
auto_penalty	auto_penalty	false	[]

Description

A rigid lock connects rigid bodies \(a\) and \(b\), preventing relative motion between them. It requires the specification of a joint origin and two orthogonal axes \(\mathbf{e}_{1}\) and \(\mathbf{e}_{2}\).

The tolerance parameter defines the augmentation tolerance. That is, when the relative change in the constraint forces and moments (the Lagrange multipliers) are less than this value. The gaptol parameter defines the tolerance for spatial separation of the joint origin on the two bodies (in units of length). The angtol parameter defines the tolerance for angular separation of the joint axes on the two bodies (in units of radians). Setting any of these three elements to zero disables the enforcement of that tolerance. The force_penalty parameter (with units of force per length) represents the stiffness that prevents the joint origin on the two bodies from separating along the rotation axis. The moment_penalty parameter (with units of moment per radians) represents the torsional stiffness that enforces parallelism of the joint rotation axis on the two bodies. The body_a and body_b parameters are the material numbers of the two rigid bodies. The joint_origin parameter defines the position of the joint (the origin of the basis \(\left\{ \mathbf{e}_{1},\mathbf{e}_{2},\mathbf{e}_{3}\right\}\)) in world coordinates at the start of the analysis. Note that this point does not have to be inside or on the surface of either of the two bodies. The first_axis element defines the orientation of the axis \(\mathbf{e}_{1}\) in world coordinates at the start of the analysis. The second_axis element defines the orientation of the second axis \(\mathbf{e}_{2}\) in world coordinates at the start of the analysis.

Example:

<rigid_connector type="rigid lock" name="Joint01">
  <tolerance>0</tolerance>
  <gaptol>1e-4</gaptol>
  <angtol>1e-4</angtol>
  <force_penalty>1e0</force_penalty>
  <moment_penalty>1e0</moment_penalty>
  <auto_penalty>1</auto_penalty>
  <body_a>1</body_a>
  <body_b>2</body_b>
  <joint_origin>0,0,0</joint_origin>
  <first_axis>1,0,0</first_axis>
  <second_axis>0,1,0</second_axis>
</rigid_connector>